Allen-Bradley 2080-LC20-20QWB User Manual page 16

Chapter 2 About Your Controller
8
RMC is useful when the user is developing a project by incrementally adding
small changes to the logic and immediately wants to see the effects of the changes
on the machine. With RMC, since the controller stays in remote run mode, the
controller logic and machine actuators will not have to constantly reinitialize,
which can occur if the controller is switched to remote program mode (for
example, first scan bit is checked in program logic to clear outputs).
When user is editing, building, and downloading a project without using RMC, a
full build of the entire controller project is performed and also a full download of
the project is performed. During RMC an incremental build is performed and
only incremental changes are downloaded to the controller.
RMC is performed incrementally at the end of every program scan in order to
prevent a large delay in the program scan. This adds up to an additional 12 ms to
the scan time. For example, if the program scan is normally 10 ms, it may increase
to 22 ms during RMC until the update is finished. Similarly user interrupts may
be delayed.
Example of the Benefits of Using RMC – 20% Reduction in Download Time
Number of Time to Perform Conventional
Changes Download (seconds)
1 103
5 241
10 376
Memory size of project used for comparison:
Data = 16704 bytes; Program = 2052 bytes
ATTENTION: Use extreme caution when you use Run Mode Change.
Mistakes can injure personnel and damage equipment. Before using Run
Mode Change:
·
assess how machinery will respond to the changes.
·
notify all personnel about the changes.
A new global variable SYSVA_PROJ_INCOMPLETE has been added to
indicate when Run Mode Changes are being made. This can be used to notify
personnel on the HMI that there are uncommitted changes in the controller.
Value of Global Variable – SYSVA_PROJ_INCOMPLETE
Value Description
0 (Default) No uncommitted changes
1 Uncommitted changes present
2 Error occurred during Test Logic Change
(for example, communications loss during Test Logic)
When you perform a Test Logic Change, the value of the variable is changed from
zero to one. After you choose to accept or undo the changes, the value of the
variable is reset to zero.
Time to Test Logic and
Accept Changes (seconds)
80
191
308
Rockwell Automation Publication 2080-UM005B-EN-E - March 2015